# Prime and composite numbers review

CCSS Math: 4.OA.B.4

Review prime and composite numbers, and try some practice problems.

## What are prime numbers?

Prime numbers are numbers with exactly $2$ factors.

A prime number's only factors are $\greenD1$ and the number $\purpleD{\text{itself}}$.

$7$ is an example of a

**prime**number. Its only factors are $\greenD1$ and $\purpleD7$. It is not evenly divisible by any other whole numbers.*Want to learn more about prime numbers? Check out this video.*

## Practice set 1: Identifying prime numbers

*Want to try more problems like this? Check out this exercise.*

## What are composite numbers?

Composite numbers have more than $2$ factors. A composite number has factors in addition to $1$ and the number $\text{itself}$.

$16$ is an example of a

**composite**number. The factors of $16$ are $1, 2, 4, 8$ and $16.$ All of these numbers divide into $16$ evenly.*Want to learn more about recognizing prime and composite numbers? Check out this video.*

*Want more ways to think about prime and composite numbers? Check out this article.*

## Practice set 2: Identifying composite numbers

*Want to try more problems like this? Check out this exercise.*